Einflußgrößen der Schwermetallöslichkeit und -bindung in Böden

Solubility and retention of heavy metals in soils Model experiments were carried out under oxidizing conditions with soil samples from surface and subsurface horizons of different composition in order to investigate the solubility and retention of Cu, Zn, Cd, and Pb in soils. The solubility of heavy metals is mainly determined by ad- and desorption processes and complexation reactions of organic and inorganic ligands. Precipitation and dissolution of definite heavy metal compounds do not seem to govern the solution concentration in soils. An exception may probably be the formation of lead phosphate and zinc silicate under specific reaction conditions. The main factors which determine solubility and retention of heavy metals are total amount (except the proportion incorporated in the silicate structure) of the different metals, soil reaction, content of mobilizing and immobilizing organic substances, content of pedogenic oxides and clay minerals, and kind and concentration of salts and inorganic ligands. The results of the model experiments are used together with the results of other authors and general physico-chemical data to give an interpretation of the solubility behaviour of heavy metals in soils. The relations between heavy metal solubility, availability and mobility and possible procedures for melioration of soils contaminated with heavy metals are discussed.     

Zur Entstehung tiefhumoser Böden in der Calenberger Lößbörde bei Hannover

Development of Thick Humic Soils in the Calenberg Fertile Loess Plain near Hannover Different thick humic soils (Gray-brown podzolic soil [Parabraunerde], Chernozem, Colluvium) in the Calenberg Fertile Loess Plain (to the north of the Deister hills) are compared with each other in terms of history, distribution of soil types, morphology and chemical composition. The distribution of Chernozem and Colluvium is determined by the morphology of the area. The thick humic Gray-brown podzolic soils seem to be the result of agricultural land use over a long period of time. The soils can be clearly distinguished by different iron and phosphorus contents and their distribution in the soil profile. The increased phosphorus content of the Gray-brown podzolic soils is probably a result of the addition of plaggen and manure. Further investigations are in progress.     

Körnung von Saproliten als methodenabhängige Größe

Particle size distribution of saprolites – a method dependent parameter Saprolites and saprolite-derived young soils contain a heavily weathered, kaolinized and more or less soft material, which is further fractured by roots, frost, tillage etc. The particle size distribution of the derived soils depends mainly on the distribution of saprolite fragments. Mechanical crushing, chemical dispersion and especially the application of ultrasonic with variable energy cause shifts in particle size distribution. In some soft saprolites the application of high energy sonication led to two- to threefold increase in clay content reaching 60%. A conventional method for preliminary mechanical treatment and for the determination of particle size distribution of saprolites and saprolitic soils is recommended.     

Bodenchemische Vertikalgradienten als charakteristische Zustandsgrößen von Waldökosystemen

Soil chemistry depth gradients as characteristic state variables of forest ecosystems Based on model concepts and on analyses of the soil solution and the soil solid phase we present a procedure to predict the cation composition of the soil solution from solid phase properties. For the intended prediction, the aluminum (or base) saturation (NH₄Cl extraction) of the soil exchange complex yields the best results. This parameter shows distinct gradients through a soil profile, and these gradients can be used to characterize the state of the ecosystem. We suggest to utilize this parameter as an additional criterion in the practice of forest site classification.     

Über die Humusdynamik in vier österreichischen Waldböden

Humus dynamics in four Austrian forest soils The humus of four Austrian forest soils was characterized by means of a chromatographic and a mass spectrometric (δ¹³C, δ¹⁵N) method. With this combination it was possible to explain changes in the humic acid systems within the profiles. The leaching of humic acids in a Spodo-Dystric Cambisol and therefore the beginning of podsolization could be deduced. In a Stagno-Dystric Gleysol processes of dehumification were determined. The value of non humic substances was enhanced within the profile of a Fluvi-Calcaric Fluvisol. The δ¹⁵N-values increased in the four profiles much more with depth than the δ¹³C-values. This indicated the rapid mineralization of organic nitrogen.     

Genese und Ökologie innerstädtischer Böden aus Bauschutt

Formation and ecology of rural soils from debris Within 30 years Rendzinas have developed on habitats of debris and rubbles in West-Berlin by accumulation of organic substances, carbonate impoverishing, slightly beginning acidity, and biogenic structuring. Their conditions for water, air, and nutrients were investigated for 2 years.     

Kurzmitteilung Ein methodischer Beitrag zur Porengrößen-Messung bei Böden

A methodic contribution for the measuring of volume of pores in soils An apparatus for determination of the soil pores in the pF-range 0–2,5, partially produced in home-work, is described. Thereby are used ceramic plates 50 × 35 cm with a thickness of 5–8 mm. The ceramic plates are sticked on 63 × 50 cm gum plates with Teroson-Cement-BE and packed in correspondingly great wooden boxes. The soil samples are dehydrated in an over-pressure chamber.     

Über die Sorptionseigenschaften von Waldböden bezüglich gelöster organischer Substanzen

About the sorption of dissolved organic matter to forest soils This investigation characterizes the major forest soils of the temperate climatic zones (leptosols, vertisols, cambisols, luvisols, podzols, stagnosols, gleysols) as sorbents for dissolved organic matter (DOM). Sorption isotherms were obtained for 135 soil horizons from 36 profiles. When solutions containing no DOC were added, the release of dissolved organic carbon (DOC) was highest for horizons rich in organic C (A and Bh horizons). In subsoil horizons DOC release was much lower. Most of the investigated top soils (A and E horizons) and Bh, Bg, and C horizons showed a weak DOC sorption. This was caused by low contents of sorbents (clay and sesquioxides) and/or high contents of organic C. Organic C seems to reduce the DOC sorption by occupying binding sites. Subsoils rich in clay and sesquioxides like Bs, Bt, and Bw horizons showed a strong retention of DOC. Under the aerobic conditions of the experiments, some of the subsoils of stagnosols and gleysols also showed a strong sorption of DOC. However, in sorption experiments conducted after an anaerobic incubation, the DOC sorption decreased significantly.     

Klimaeinfluß auf Lignin und Polysaccharide in Partikelgrößen-Fraktionen zonaler Steppenböden Rußlands

Climatic effect on lignin and polysaccharides in particle-size fractions of zonal steppe soils, Russia Zonal soils derived from similar parent materials are suitable for investigating the question, whether and how climate affects soil organic matter properties. For this reason we sampled 10 native surface (0—10 cm) and subsurface (ca. 50—60 cm) soil horizons in the native steppe and forest steppe of Russia. Polysaccharides and the vanillyl, syringyl and cinnamyl structural units of lignin (VSC) were determined in the fine earth (< 2 mm) as well as in clay (< 2 μm) and silt (2—20 μm) fractions. As the ratio of mean annual precipitation to potential evaporation (N/V) decreased, the concentrations of polysaccharides tended to decrease in the subsoil horizons. This was indicated most clearly for the silt fractions (r = 0.98**). In contrast, the VSC contents (in g kg^—1 organic C) of the subsoils increased as N/V decreased (r = —0.92*), resulting in increasing VSC/polysaccharide ratios of the subsoil horizons with decreasing N/V ratio (r = —0.94*). It is suggested that production of polysaccharides or their transport into the mineral subsoil or both is favored at sites with wide rather than narrow N/V ratio, whereas lignin might be selectively enriched during intense soil organic matter decay at the Southern sites.     

Ökologische Gruppierung von Böden nach ihrem chemischen Bodenzustand

Ecological grouping of soils according to their chemical soil state On the base of the solubility of carbonic acid, calcium carbonate, as well as the oxidic compounds of Al and Fe existing in soils, the following buffer ranges are defined and separated from each other by pH values in the soil solution: Carbonic acid/Carbonate buffer range (pH 6.2 to 8.6), Carbonic acid/Silicate buffer range (pH 5.0 to 6.2), Exchanger buffer range (pH 4.2 to 5.0), Aluminium buffer range (pH 2.8 to 4.2), Iron buffer range (pH 2.4 to 3.8). The buffer capacities are calculated and literature indications regarding buffer rates are compiled. The characteristical chemical soil state is demonstrated for the various buffer ranges with aid of a soil collection. With increasing soil acidification the Ca/Al mole ratio in fine roots decreases from values > 1 to values around 0.3; this is taken as evidence for increasing disposition for Al-toxicity. It is suggested to attach soil horizons to buffer ranges on the base of pH(H₂O) measurements made on field fresh samples. The measurement of pH in salt solution is taken as measure for the amplitude of the chemical soil state in case of H-ion or salt stress.     

Möglichkeiten der Verwertung von Rotschlamm und Grünsalz auf Hochmoorböden

Practicable application of red sludge and melanterite (FeSO₄) on bog peat soils A new way is shown to dispose the industrial by-products red sludge and melanterite by agricultural application. The ferrous products sorbe the moveable phosphates in the acid bog peat soil, so that they are still available for plants, but will not or only a little be leached. In a field trial the amount of leached phosphorus could be reduced by about 80%. The agricultural use of red sludge and melanterite is thereby at the same time a contribution to reduce the pollution of surface waters.     

Adsorptionsisothermen als Regelgrößen beim Transport von Schwermetallen in Böden

Adsorption isotherms as regulators controlling heavy metal transport in soils The adsorption and desorption of Pb²⁺ and Cd²⁺ from equilibrium solutions with heavy metal contents up to 5000 μg/1 were determined in bulk experiments for soil samples from an acid Braunerde developed in loess loam, taken from the humic surface layer of the mineral soil (0–10 cm) and from the subsoil fairly free from organic matter (30–40 cm). Pb and Cd in solutions were determined by flameless atomic absorption spectroscopy. Pb was more strongly retained in the solid phase than Cd, and higher amounts of heavy metals were retained in the humic surface soil than in the subsoil free of organic matter. In the case of Pb adsorption/desorption showed slight hysteresis in the subsoil. The quantity/intensity (Q/I) relationships found in the experiments could be described by the Freundlich equation. The Q/I-relationships were substituted in the general transport equation. With a simulation model the transport of Pb and Cd through the soil with vertical water flow was calculated by the use of the Continuous Simulation Programming Language (CSMP). Two different cases were considered: a small, continuous increase in the heavy metal input of the soil surface, and a high, instantaneous peak input. Simulation of the transport and distribution mechanisms induced by the inputs over a period of 10 years showed strong retention of lead in the surface layer and consequently a strong damping of the concentration peak in the soil solution. In contrast, cadmium is distributed more quickly over the whole profile, yet the concentration peak in the solution phase is, too, damped considerably in the surface layer by temporary retention in the solid phase. The results of the simulation runs are in accordance with the situation in real soils where often strong accumulation of Pb is found in the top soil, while Cd is accumulated only slightly.     

Die kurzfristige pH-Pufferung von gestörten und ungestörten Waldbodenproben

Short-timed pH-buffering of disturbed and undisturbed forest soil samples The pH buffering of disturbed and undisturbed soils under spruce (podzol and podzolic cambisol derived from phyllite, eutric cambisol derived from basalt) was studied in the laboratory by adding H₂SO₄ in ecologically relevant concentrations (pH 5.6–2.0). For the cambisol with crumb structure no difference was found. 80–90% of the added protons were neutralized by release of Ca and Mg. Disturbed samples of the podzol buffer less than 70% of the applicated acid. For undisturbed samples the maximum buffering rate of 185 g H⁺/ha · h is reached with a proton load of about 500 g H⁺/ha · h (related to 4 cm soil depth). Buffering behaviour of the podzolic cambisol lies between the podzol and the cambisol. 70–90% of the proton input is buffered in the disturbed samples while the undisturbed one does not reach its maximum buffering rate, even with high proton load. In this soil Al-release is the most reactive buffer.     

Bodenhydrologische Methoden zur Untersuchung ungestörter,skelettreicher Böden

Soil hydrological methods for investigations on undisturbed samples of skeleton-rich soils New methods are proposed, which allow the determination of moisture transmission properties of stony soils. A soil sampling technique is discussed whereby small monoliths are isolated from the surrounding soil and covered with polyester-soaked glassfiber sheets. With use of such irregularly shaped columns the soil moisture characteristic and the unsaturated hydraulic conductivity are determined by laboratory procedures. Starting with a saturated column, suction is applied and the resulting outflow is measured. At the same time the suction in the sample is registered and also the hydraulic gradient within the sample is determined. Also discussed is a procedure to install tensiometers in stony soils. The installation provides reliable data and the maintenance is easy. By building in a heating system in the tensiometers, these can be operated all year round.     

Der Einfluß einer Kalkung auf Aggregatstabilität und Eindringwiderstand zweier Lößböden

Aggregate Stability and Penetration Resistance of two Normal and Limed Soils To investigate the meliorative effect of liming, the aggregate stability (determined by wet sieving and sedimentation) and the penetration resistance (by a previously described method (Becher 1973 a) of unlimed and limed samples of two field experiments on a Brown Earth-Pseudogley and a Humic Pseudogley were determined. Penetration resistance decreased with decreasing water suction, but it did not show significant relation to liming. Aggregate stability was increased by liming on the Brown Earth-Pseudogley but was lowered on the Humic Pseudogley, while penetration resistance was only influenced in some cases. The behaviour of the Humic Pseudogley was explained by its exceptional high organic matter content (5–6%).